American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 184133 bytes)

GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L12S02, doi:10.1029/2006GL025770, 2006

The effect of pressure on the structure and volume of ferromagnesian post-perovskite

Wendy L. Mao

Los Alamos Neutron Science Center, Los Alamos National Laboratory, Los Alamos, New Mexico, USA


Ho-kwang Mao

Geophysical Laboratory, Carnegie Institution of Washington, Washington, D. C., USA


Vitali B. Prakapenka

GeoSoilEnviroCARS, University of Chicago, Chicago, Illinois, USA


Jinfu Shu

Geophysical Laboratory, Carnegie Institution of Washington, Washington, D. C., USA


Russell J. Hemley

Geophysical Laboratory, Carnegie Institution of Washington, Washington, D. C., USA


Abstract

We determined pressure-volume (P-V) data for (Mg0.6Fe0.4)SiO3 post-perovskite (ppv) upon decompression from 140 GPa. The data can be divided into four regions: above 95 GPa, diffraction peaks are sharp and follow a smooth and tight P-V curve; below 90 GPa, peak widths increase, and a kink develops in the P-V curve; below 60 GPa, the broadening plateaus; below 4.6 GPa, the ppv pattern disappears. This suggests that defects and stacking faults start to develop in ppv at 90 GPa and saturate at 60 GPa, and the structure disintegrates below 4.6 GPa. The volume and density of the (Mg0.6Fe0.4)SiO3 ppv is well constrained by our data at the pressures relevant to the Earth's D″ layer. Our bulk modulus in this region is much higher than theoretical calculations for pure MgSiO3 ppv.

Received 13 January 2006; accepted 27 March 2006; published 5 May 2006.

Index Terms: 3919 Mineral Physics: Equations of state; 3924 Mineral Physics: High-pressure behavior; 3954 Mineral Physics: X-ray, neutron, and electron spectroscopy and diffraction.

Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 184133 bytes)

Citation: Mao, W. L., H. Mao, V. B. Prakapenka, J. Shu, and R. J. Hemley (2006), The effect of pressure on the structure and volume of ferromagnesian post-perovskite, Geophys. Res. Lett., 33, L12S02, doi:10.1029/2006GL025770.